In recent years, the use of organic EL display panels including a substrate and a matrix of organic EL elements arranged over the substrate have been put into practical use. Such an organic EL display panel achieves high visibility due to the organic EL elements performing light emission individually. Also, such an organic EL display panel achieves excellent shock resistance due to the organic EL elements being completely solid-state elements.
Organic EL elements in a typical organic EL display panel have a basic structure in which a light-emitting layer containing an organic light-emitting material is disposed between an electrode pair composed of an anode and a cathode. The organic EL elements are driven through voltage application between these electrodes. The organic EL elements are current-driven light-emitting elements, emitting light when holes injected into the light-emitting layer from the anode and electrons injected into the light-emitting layer from the cathode recombine in the light-emitting layer.
In a typical organic EL display panel, a light-emitting layer of one organic EL element is partitioned from a light-emitting layer of an adjacent organic EL element by a bank formed from an electrically-insulative material.
Further, one or more organic layers, such as a hole injection layer, a hole transport layer, and a hole injection/transport layer are disposed as necessary between the anode and the light-emitting layer. Likewise, one or more organic layers, such as an electron injection layer, an electron transport layer, and an electron injection/transport layer are disposed as necessary between the cathode and the light-emitting layer.
In a full color organic EL display panel, a plurality of such organic EL elements are disposed, and each organic EL element serves as a red sub-pixel, a green sub-pixel, or a blue sub-pixel. Further, each pixel of a full-color organic EL display panel is composed of a set of red, green, and blue sub-pixels disposed next to one another.
The manufacturing of such an organic EL display panel involves a process of forming light-emitting layers and so on in concave spaces defined by banks, after forming the banks on the substrate. The forming of the light-emitting layers is often performed through a wet process of applying, to the concave spaces, an ink for light-emitting layer formation containing a macro-molecular material or a low-molecular material suitable for forming a thin film, through an inkjet method or a similar method. Such a wet process enables organic layers and light-emitting layers to be formed relatively easily, even in large panels.